Dynamics of wind-driven upwelling and relaxation between Monterey Bay and Point Arena: Local-, regional-, and gyre-scale controls

In north and central California, equatorward winds drive equatorward flows and the upwelling of cold dense water over the shelf during the midspring and summer upwelling season. When the winds temporarily weaken, the upwelling flows between Point Reyes and Point Arena relax,\u27\u27 becoming strongly poleward over the shelf. Analytical and numerical models are used to describe the effect of alongshore variability of winds, bathymetry, and basin-scale pressure gradients on the strength of upwelling and its relaxation. Alongshore winds weaken to the south of Point Reyes, and the shelf becomes narrower from Point Reyes to Monterey Bay. Both of these lead to reduced upwelling at and to the north of Point Reyes, causing an alongshore gradient of temperature and density on the shelf. These alongshore gradients lead to an along-isobath pressure gradient over the shelf that drive the relaxation flows. A simple analytical model is used to explain the dynamics, magnitude, and structure of the relaxation flows. The modeling also suggests that the depth of origin of the upwelled waters, and thus their temperature, is controlled by the along-isobath pressure gradient that exists over the continental slope. This along-slope pressure gradient is also responsible for the California undercurrent in this region. This pressure gradient is not generated in a model of the Californian coast extending from 32 degrees N to 42 degrees N and integrated for several months, suggesting it is caused by dynamics whose spatial or temporal scales are larger than the Californian coast and/or longer than several months

Chemical vapor deposited silica coatings for solar mirror protection

A variety of techniques is available to apply protective coatings to oxidation susceptible spacecraft components, and each has associated advantages and disadvantages. Film applications by means of chemical vapor deposition (CVD) has the advantage of being able to be applied conformally to objects of irregular shape. For this reason, a study was made of the oxygen plasma durability of thin film (less than 5000 A) silicon dioxide coatings applied by CVD. In these experiments, such coatings were applied to silver mirrors, which are strongly subject to oxidation, and which are proposed for use on the space station solar dynamic power system. Results indicate that such coatings can provide adequate protection without affecting the reflectance of the mirror. Scanning electron micrographs indicated that oxidation of the silver layer did occur at stress crack locations, but this did not affect the measured solar reflectances. Oxidation of the silver did not proceed beyond the immediate location of the crack. Such stress cracks did not occur in thinner silica flims, and hence such films would be desirable for this application

The effect of leveling coatings on the atomic oxygen durability of solar concentrator surfaces

Space power systems for Space Station Freedom will be exposed to the harsh environment of low earth orbit (LEO). Neutral atomic oxygen is the major constituent in LEO and has the potential of severely reducing the efficiency of solar dynamic power systems through degradation of the concentrator surfaces. Several transparent dielectric thin films have been found to provide atomic oxygen protection, but atomic oxygen undercutting at inherent defect sites is still a threat to solar dynamic power system survivability. Leveling coatings smooth microscopically rough surfaces, thus eliminating potential defect sites prone to oxidation attack on concentrator surfaces. The ability of leveling coatings to improve the atomic oxygen durability of concentrator surfaces was investigated. The application of a EPO-TEK 377 epoxy leveling coating on a graphite epoxy substrate resulted in an increase in solar specular reflectance, a decrease in the atomic oxygen defect density by an order of magnitude and a corresponding order of magnitude decrease in the percent loss of specular reflectance during atomic oxygen plasma ashing

Simulation of the synergistic low Earth orbit effects of vacuum thermal cycling, vacuum UV radiation, and atomic oxygen

In order to assess the low Earth orbit (LEO) durability of candidate space materials, it is necessary to use ground laboratory facilities which provide LEO environmental effects. A facility combining vacuum thermal cycling and vacuum ultraviolet (VUV) radiation has been designed and constructed at NASA Lewis Research Center for this purpose. This facility can also be operated without the VUV lamps. An additional facility can be used to provide VUV exposure only. By utilizing these facilities, followed by atomic oxygen exposure in an RF plasma asher, the effects of the individual vacuum thermal cycling and VUV environments can be compared to the effect of the combined vacuum thermal cycling/VUV environment on the atomic oxygen durability of materials. The synergistic effects of simulated LEO environmental conditions on materials were evaluated by first exposing materials to vacuum thermal cycling, VUV, and vacuum thermal cycling/VUV environments followed by exposure to atomic oxygen in an RP plasma asher. Candidate space power materials such as atomic oxygen protected polyimides and solar concentrator mirrors were evaluated using these facilities. Characteristics of the Vacuum Thermal Cycling/VUV Exposure Facility which simulates the temperature sequences and solar ultraviolet radiation exposure that would be experienced by a spacecraft surface in LEO are discussed. Results of durability evaluations of some candidate space power materials to the simulated LEO environmental conditions will also be discussed. Such results have indicated that for some materials, atomic oxygen durability is affected by previous exposure to thermal cycling and/or VUV exposure

Isotopic study of oxygen diffusion in oxide coatings

Diffusion of oxygen in thin films of silicon dioxide was studied using oxygen isotopically enriched in oxygen of atomic mass 18 (O-18). This subject is of interest because thin films of dielectrics such as SiO2 are proposed for use as a protective coatings for solar mirrors in low Earth orbit, which is a strongly oxidizing environment. Films of this material were prepared with a direct current magnetron using reactive sputtering techniques. To produce (O-18)- enriched SiO2, a standard 3.5-in.-diameter silicon wafer was reactively sputtered using (O-18)-enriched (95 percent) oxygen as the plasma feed gas. The films were characterized using Rutherford backscattering and Secondary Ion Mass Spectrometer (SIMS) to establish stoichiometry and purity. Subsequently, the films were exposed to an air-derived oxygen plasma in a standard laboratory plasma reactor for durations of up to 10 hr. The concentration ratio of O-16 as a function of depth was determined using SIMS profiling and compared to a baseline, nonplasma exposed sample. A value for the diffusivity of oxygen near the surface of these films was obtained and found to be about 10(-15)sq cm/sec

Evaporation of ices near massive stars: models based on laboratory TPD data

Hot cores and their precursors contain an integrated record of the physics of the collapse process in the chemistry of the ices deposited during that collapse. In this paper, we present results from a new model of the chemistry near high mass stars in which the desorption of each species in the ice mixture is described as indicated by new experimental results obtained under conditions similar to those hot cores. Our models show that provided there is a monotonic increase in the temperature of the gas and dust surrounding the protostar, the changes in the chemical evolution of each species due to differential desorption are important. The species H$_2$S, SO, SO$_2$, OCS, H$_2$CS, CS, NS, CH$_3$OH, HCOOCH$_3$, CH$_2$CO, C$_2$H$_5$OH show a strong time dependence that may be a useful signature of time evolution in the warm-up phase as the star moves on to the Main Sequence. This preliminary study demonstrates the consequences of incorporating reliable TPD data into chemical models.Comment: 5 pages, accepted by MNRA

Child Anxiety Sensitivity in Juvenile Adolescent Twins

Child Anxiety Sensitivity in Juvenile Adolescent Twins. Researched by Laura Hazlett from the VCU Psychology Department. Help from faculty mentors Dr. John Hettema, Psychiatry and Dr. Roxann Roberson-Nay, Psychology. Anxiety sensitivity (AS) is a dispositional trait where one is fearful of anxiety symptoms, and is distinguishable from the trait of anxiety itself. (Eke & McNally, 1996). These fears of anxiety-related sensations are an important factor in predicting the emergence and severity of panic symptoms (McNally, 2002). The Child Anxiety Sensitivity Index (CASI) is the child version of an 18-item self-report questionnaire commonly used to measure anxiety sensitivity. Zinbarg et al. (1997) demonstrated that the ASI has three first-order factors: Physical Concerns (i.e. “It scares me when my heart beats fast “), Mental Incapacitation Concerns (i.e. “When I am afraid, I worry that I might be crazy”), and Social Concerns (i.e. “Other kids can tell when I feel shaky “). The aim of the current study is to examine the relationship between scores on the CASI and responses during a low-dose carbon dioxide breathing task designed to induce panic-related sensations. The participants in our study were monozygotic and dizygotic twin pairs ranging from ages nine to thirteen. Twins’ responses throughout the task were measured using the Subjective Units of Distress Scale (SUDS) and the Diagnostic Symptom Questionnaire (DSQ), which measures cognitive and physical panic symptoms. We hypothesize that there is a positive relationship between the CASI and anxious responding during the carbon dioxide breathing task, such that as CASI scores increase, so do scores on the DSQ and SUDS. The results support the hypothesis and show significant evidence of a relationship between the CASI and subjectively experienced distress and panic symptoms. So, the more fearful an individual is of panic symptoms, the more severely they experience those symptoms, which in turn causes greater subjective distress. This study contributes to identifying the overall relationship between the CASI, DSQ, and SUDS scores when looking at physical, mental, and social concerns that contribute to the fear of experiencing subjective anxious symptoms.https://scholarscompass.vcu.edu/uresposters/1058/thumbnail.jp

Application of Autonomous Spacecraft Power Control Technology to Terrestrial Microgrids

This paper describes the potential of the power campus located at the NASA Glenn Research Center (GRC) in Cleveland, Ohio for microgrid development. First, the benefits provided by microgrids to the terrestrial power grid are described, and an overview of Technology Needs for microgrid development is presented. Next, GRC's work on development of autonomous control for manned deep space vehicles, which are essentially islanded microgrids, is covered, and contribution of each of these developments to the microgrid Technology Needs is detailed. Finally, a description is provided of GRC's existing physical assets which can be applied to microgrid technology development, and a phased plan for development of a microgrid test facility is presented

Differing roles of autophagy in HIV-associated neurocognitive impairment and encephalitis with implications for morphine co-exposure

We investigated the role of autophagy in HIV-infected subjects with neurocognitive impairment (NCI) ± HIV encephalitis (HIVE), many of which had a history of polysubstance abuse/dependence, using post-mortem brain tissues to determine whether differences in autophagy related factors may be more associated with NCI or NCI-encephalitis. Using qRT-PCR, we detected significant differences in gene expression levels with SQSTM1, LAMP1 higher in HIV-infected subjects without NCI while ATG5, SQSTM1 were then lower in HIV infection/NCI and ATG7, SQSTM1 being higher in NCI-HIVE. Immunohistochemical labeling of these autophagy associated proteins (also including Beclin 1 and LC3B) in Iba1-positive microglial cells showed generally higher immunoreactivity in the NCI and NCI-HIVE groups with more focal vs. diffuse patterns of expression in the NCI-HIVE group. Furthermore, analysis of microarray data from these same subjects found significantly higher levels of LAMP1 in NCI-HIVE compared to uninfected subjects in the basal ganglia. Finally, we tested the effect of supernatant from HIV-1-infected microglia and HIV-1 Tat protein in combination with morphine on neurons in vitro and found opposing events with both significant inhibition of autophagic flux and reduced dendrite length for morphine and supernatant treatment while Tat and morphine exposure resulted in lower autophagic activity at an earlier time point and higher levels in the later. These results suggest autophagy genes and their corresponding proteins may be differentially regulated at the transcriptional, translational, and post-translational levels in the brain during various stages of the HIV disease and that infected individuals exposed to morphine can experience mixed signaling of autophagic activity which could lead to more severe NCI than those without opioid use

Overview of Intelligent Power Controller Development for Human Deep Space Exploration

Intelligent or autonomous control of an entire spacecraft is a major technology that must be developed to enable NASA to meet its human exploration goals. NASA's current long term human space platform, the International Space Station, is in low Earth orbit with almost continuous communication with the ground based mission control. This permits the near real-time control by the ground of all of the core systems including power. As NASA moves beyond low Earth orbit, the issues of communication time-lag and lack of communication bandwidth beyond geosynchronous orbit does not permit this type of operation. This paper presents the work currently ongoing at NASA to develop an architecture for an autonomous power control system as well as the effort to assemble that controller into the framework of the vehicle mission manager and other subsystem controllers to enable autonomous control of the complete spacecraft. Due to the common problems faced in both space power systems and terrestrial power system, the potential for spin-off applications of this technology for use in micro-grids located at the edge or user end of terrestrial power grids for peak power accommodation and reliability are described